JPH04191105A - Radial tire - Google Patents

Abstract

PURPOSE:To make only stiffness high in the circumferential direction of a tire by arranging a rubber compound layer which includes organic short fibers arranged in the circumferential direction of the tire, in the side walls. CONSTITUTION:Each side wall 10 is formed into a three ply structure where a surface layer 11, a rubber compound layer 12 and a bonding layer 13 are laminated in order from the outside. The rubber compound layer 12 is formed while organic single fibers such as nylon, polyester and the like which are arranged in the circumferential direction, are contained in rubber compound base material. In this case, the volume content of organic single fibers in the rubber compound 12 is set at 5 to 20%, and weather resistance is made high with high weather resistant rubber applied to the surface layer 11. By this constitution, tire stiffness in the longitudinal direction can thereby be made high with no tire stiffness changed in the lateral direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a radial tire that has increased rigidity only in the tire circumferential direction compared to conventional tires.

[Prior Art and Problems to be Solved by the Invention] Radial tires generally have low rigidity in the tire circumferential direction because the cords in the carcass are oriented in the radial direction.

Now, phenomena such as road noise (muffled noise inside the car) that occurs when driving on uneven roads with tires installed, and harshness shock that is transmitted to passengers when the tires go over bumps, are important for vehicle comfort. This is a serious problem. It is known that vibrations in the torsional mode of the tire are mainly related to these phenomena, and road noise and harshness shock can be alleviated by increasing the torsional rigidity of the tire, that is, the circumferential rigidity.

One possible way to increase the circumferential rigidity of a tire is to first increase the rigidity of the sidewall by changing the tire shape. It is also possible to add reinforced braais with embedded cords to the sidewalls.

However, with these measures, it is not possible to change only the circumferential stiffness of the tire independently, but the stiffness in the radial and lateral directions also changes at the same time, causing changes in other performances such as handling stability and ride comfort. There was a problem with it.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radial tire that has greater rigidity only in the circumferential direction than conventional tires.

[Means for Solving the Problems] In order to solve the above problems, the radial tire according to the present invention is one in which a rubber composite layer containing organic single fibers oriented in the circumferential direction of the tire is arranged on the sidewall. .

The volume content of organic single fibers in the rubber composite layer is 5 to 20
%.

[Function] A rubber composite material in which organic single fibers are oriented in one direction in a rubber base material can be obtained by extruding rubber mixed with organic single fibers. Simply by performing extrusion, the organic single fibers are oriented in the extrusion direction. This rubber composite material is formed into a sheet, and this is applied as a layer as part of the sidewall. At this time, the orientation direction of the organic single fibers in the rubber composite material is made to coincide with the tire circumferential direction.

A rubber composite material in which organic single fibers are oriented in one direction has a higher elastic modulus in the organic single fiber orientation direction than a rubber material that does not contain organic single fibers. However, the elastic modulus in the width direction and thickness direction hardly changes. For this reason, in a radial tire in which a rubber composite material layer containing organic single fibers oriented in the tire circumferential direction is arranged on the sidewall, only the rigidity in the tire circumferential direction increases, and the tire rigidity in the radial and lateral directions hardly changes. do not.

The volume content of the organic single fibers is preferably in the range of 5 to 20%. If the content is less than 5%, no change in rigidity can be expected. Conversely, the higher the content, the greater the tire circumferential rigidity, but if the content exceeds 20%, the extrusion workability deteriorates. Further, the problem arises that the rubber composite layer is more likely to crack. If the content is in the range of 5 to 20%, the weight of the sidewall will increase only slightly compared to the case where the organic single fibers are not included. Furthermore, compared to the case where reinforcing braais with embedded cords are added to the sidewalls as described above, the increase in weight of the tire can be suppressed to a lower level.

[Example] FIG. 1 is a half-sectional view of a radial tire according to an example of the present invention.

The carcass I reaches the bead portion from the tread portion via the side portion, is folded back to the outside while winding up the bead wire 2 and bead filler 3, and then the end portion is locked. The locking end of the bead of the carcass I is covered with a rim strip 4. However, in the carcass I, the organic fiber cords are buried parallel to each other at an angle of about 90@ to the tire circumferential direction.

In the tread portion, the carcass l is restrained by a belt 5 made of a plurality of plies, and then a tread 6 is provided on the belt 5. However, in each fly constituting the belt 5, steel cords are arranged parallel to each other at a small angle with respect to the tire circumferential direction.

A side wall 10 is provided at the side portion and covers the side portions of the carcass 1 and the tread 6.

The lower end of this sidewall lO is the rim strip 4
◎ The sidewall 10 shown in the figure has a three-layer structure consisting of a surface layer 11, a rubber composite layer 12, and an adhesive layer 13 in order from the outside.

The rubber composite layer 12 contains organic single fibers such as nylon, polyester, aramid, vinylon, etc. oriented in the tire circumferential direction in a rubber composition base material.

For example, in the case of nylon single fiber, the diameter is 0.005 to 0.
．． The use of single fibers of 8 μm and length of 10 to 1000 μm is preferred. The volume content of the organic single fibers is suitably in the range of 5 to 20%.

In the embodiment shown in the figure, a surface layer 11 made of rubber with good weather resistance is disposed on the outside of the rubber composite layer 12 in order to particularly ensure the weather resistance of the sidewall 1 [1. This surface layer 1
Arrangement 1 also has the effect of maintaining the aesthetic appearance of the tire. Also,
In order to ensure adhesion between the sidewall lO and other rubber parts, an adhesive layer 13 made of rubber with excellent adhesion to other rubber parts is arranged inside the rubber composite layer 12.

Now, regarding the radial tire having the sidewall 10 with the three-layer structure described above, the calculated value of the elastic modulus of the material and the calculated value of the torsional rigidity of the tire obtained by the finite element method using this are shown in Example 1 and 2 in Table 1. The values for the conventional example in the same table indicate the case where the sidewall does not contain organic single fibers. However, the torsional rigidity of a tire is calculated by applying an internal pressure of 2 kg/cm2 to a tire model with a sidewall having the elastic modulus (in two directions) shown in the same table.
It is calculated from the torsion angle (unit: rad) when a torque of 38,100 kgf·mm is applied in the circumferential direction of the tire.

(Margins below) In the radial tires of Examples 1 and 2 in Table 1, the sidewall IO has a rubber composite layer 12 in which polyester single fibers are oriented in the tire circumferential direction, so that the torsional rigidity of the tire, i.e. Increased circumferential rigidity. Therefore, torsional mode vibration of the tire is suppressed, and road noise and harshness shock are alleviated. Moreover,
As shown in the same table, the elastic modulus of the sidewall 10 in the direction perpendicular to the inner direction of the monofilament box does not change much compared to the case where the monofilament is not included, so the rigidity in directions other than the tire circumferential direction is different from that of the rubber composite. By providing the material layer 12, there is almost no change, and other performances such as steering stability and riding comfort do not change.

In addition, as shown in FIG. 2, the surface layer 11 and the rubber composite layer 1
A sidewall IO having a two-layer structure with 2 and 2 may be adopted. The rubber composite material layer 12 is made of organic single fibers oriented in the circumferential direction of the tire, as in the case of FIG. Even with this radial tire, only the rigidity in the tire circumferential direction can be increased compared to conventional tires.

[Effects of the Invention] As explained above, the radial tire according to the present invention has a rubber composite material layer containing organic single fibers oriented in the circumferential direction of the tire arranged on the sidewall, so it is different from conventional tires. Compared to this, only the stiffness in the tire circumferential direction increases, and the tire stiffness in the radial and lateral directions hardly changes. Therefore, road noise and noise shock can be alleviated without changing performance such as steering stability and ride comfort. Additionally, there is no need to make major changes to conventional tire manufacturing operations.

When adopting a volume content of organic single fibers in the range of 5 to 20%, it is possible to ensure workability in extrusion work for manufacturing rubber composites and to prevent cracks in the rubber composites. However, it is possible to achieve a certain improvement in tire circumferential rigidity. Further, if the content is in the range of 5 to 20%, the weight of the sidewall will increase only slightly compared to the case where the organic single fibers are not included. Furthermore, compared to the case where a reinforcing ply with embedded cords is added to the sidewall as described above, an increase in the weight of the tire can be suppressed, leading to a reduction in the weight of the tire.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view of a radial tire according to an embodiment of the present invention, and FIG. 2 is a half-sectional view of a radial tire according to another embodiment of the present invention. Explanation of symbols IO...Side wall, 11...Surface layer, 12.
... Rubber composite material layer, 13... Adhesive layer. Patent applicant: Toyo Tire & Rubber Industries, Ltd., a master engineer.

Claims (1)

[Scope of Claims] 1. A radial tire in which a rubber composite layer containing organic single fibers oriented in the circumferential direction of the tire is disposed on the sidewall. 2. The volume content of organic single fibers in the rubber composite layer is 5 to 2.
The radial tire according to claim 1, wherein the content is 0%.